The prime objective of this investigation is to establish, using large numbers of fresh axenic isolates, if positive correlation exists between Pathogenicity of Trichomonas vaginalis for Laboratory Rodents and Vertebrate Cell Cultures and pathogenicity of these strains, as estimated on the basis of the Severity of Vaginal and Cervical Disease. In all instances, clinical, microbiologic, as well as histo- and cytopathologic investigations are to be pursued at the Johns Hopkins University School of Medicine, while the primarily parasitologic studies will be conducted primarily at the University of Massachusetts/Amherst. To ascertain if the pathologic changes in the patients can be ascribed primarily or exclusively to the trichomonads, the patients' urogenital tracts will be examined for the presence of Bacteria, Fungi, and Viruses (a total of 15 organisms). In addition, correlation will be sought between In Vitro Growth Characteristics and Virulence of the strains and search is to be made for the Most Sensitive Pathogenicity Evaluation Methods of trichomonads in laboratory rodents and cell cultures. The effect of Intrinsic and Extrinsic Factors that may affect pathogenicity are also to be studied. The former entail the genetic constitution (to be studied primarily by DNA plus RNA-dependent transformation of Trichomonas gallinae) and the characteristics controlled directly by the genome (e.g. antigenic properties, surface saccharides). The intrinsic factors include also lysogenic viruses, silent virus systems, plasmids, and other extrachromosomal elements of biologic significance. The extrinsic factors (e.g. toxic substances), as referred to herein, include the chemical and biologic constituents of the infection sites.